Recently, as a demand for portable electronic products such as laptop personal computers and cellular phones increases, a demand for flat panel displays (FPD) having a small thickness and light weight increases. Among FPDs, particularly, liquid crystal displays (LCD), compared with other displays having the same screen size, have a light weight and a small volume and operate at lower power, thereby being generally used recently.
LCDs convert an inputted electric signal into visual information and transmit an image by using properties of a liquid crystal that is an intermediate material between a liquid and crystals, in which the liquid crystal varies in optical transmittance due to electrooptic modulation according to an applied voltage while being disposed between polarizer pairs. That is, a general LCD is formed of two substrates provided with an electrode and a liquid crystal is injected between the substrates and an electric field is applied to the liquid crystal by applying a voltage to two substrates, in which arrays of liquid crystal molecules are changed and optical transmittance between polarizer pairs is changed.
It is due to dielectric constant anisotropy of the liquid crystal that the liquid crystal is changed in array according to the electric field. That is, liquid crystal molecules have properties, in which a long axis direction and a short axis direction differ in dielectric constant. Due thereto, when an electric field is applied, electric forces acting in the long axis direction and the short axis direction differ. A difference between the electric forces becomes a driving source for rotating liquid crystal molecules. The liquid crystal, depending on the type, has positive dielectric constant anisotropy or negative dielectric constant anisotropy. That is, based on the long axis direction of the liquid crystal, when an electric field is applied, the former is arranged to be parallel to a direction of the electric field and the latter is arranged to be perpendicular to the direction of the electric field.
The liquid crystal also has refractive index anisotropy, which allows transmittance of light to vary with an alignment state of the liquid crystal. However, the refractive index anisotropy of the liquid crystal causes a narrowing of a viewing angle in LCDs. The viewing angle indicates a direction, in which a viewer sees a display screen. An image of the LCD is more distorted in flank than in front in such a way that the viewing angle thereof is narrower than other display devices. This is, when the liquid crystal is arranged to slant to the front, although a certain amount of light is transmitted in the front and a proper image is shown but light is not transmitted in flank, to which the liquid crystal slants, due to the refractive index anisotropy of the liquid crystal and the image may be distorted.
To overcome a limitation in the viewing angle of the LCD, a single pixel may be divided into areas and liquid crystals in the respective areas may be arranged to slant to different directions. That is, in respective areas of each pixel, multi-domains according to liquid crystal array directions are formed. When liquid crystals in a first area are arranged to slant in a first direction and liquid crystals in a second area are arranged to slant in a second direction, although light is not transmitted through the liquid crystals in the first area from one side, since the light may be transmitted through the liquid crystals in the second area, a viewing angle of an LCD may increase.
Multi-domain LCDs have an excellent viewing angle but are not formed with azimuthal anchoring energy.
On the other hand, recently, multi-stable LCDs of forming multi-patterns having a submicro size on an alignment film have been provided. Multi-stable LCDs may preserve contents without electric regeneration due to multi-array layers having a submicro size although power is turned off. Patterns having the submicro size are formed using one of multi-rubbing, multi photo arrangement, nano-imprinting, etc.
However, methods of forming patterns having a submicro size as described above do not have a high yield, are difficult to be applied to a large sized panel, and do not adjust alignment of a liquid crystal director.